Relations Between Soundboard，chord Hammer And Acoustic Radiation Of Upright Piano

Among all parts of piano, its soundboard and chord hammer are especially important tothe tone quality. This thesis researches both soundboard and chord hammers by using existingFEM of piano soundboard to solve real problems and recording the sound pressure in ananechoic chamber to research chord hammers.While using the FEM of piano, this thesis comes up with the general method of using themodal at first which including modal analysis and the curve of output power. After that,physical mechanism of soundboard are researched by using the FEM. The author concludesthat vibration energy propagates better in the grain direction than the direction perpendicularto grain, ribs enhance the stiffness of soundboard, ribs make vibration energy propagate tomore soundboard area and ribs can lead to better curve of output power. At last, the authoruses the general method to find a way to improve the low frequency characteristic of piano byadding3short ribs. According to the result of simulation, the short ribs enhance the mass ofsoundboard which results in smaller modal frequency and the low frequency output powerrise by about5dB because of it.In the experimental research of chord hammers, this thesis designs the experiment inwhich3kinds of dynamic are used to play the piano and2microphones are used to record theintermediate frequency and high frequency output better, according to the theory of Donald E.Hall. The author also record the output of a high-grade piano and threat that as the referencestandard. Hamming window of1024points is appropriate in the spectral analysis. Byobserving the differences between hammers to be tested and reference standard, the authorconclude that spectrums under weak dynamic and strong dynamic are more different than that under medium dynamic, strong dynamic is better in intermediate and high frequency rangeand weak dynamic is better in low frequency range.